Dual pressure work rest



Feb. 8, 1966 R. E. PRICE DUAL PRESSURE WORK REST Filed May 5, 1962 INVENTOR RALPH E. PRICE ATTORNEY United States Patent 3,233,368 DUAL PRESSURE WORK REST Ralph E. Price, l Vayneshoro, Pa., assignor to Landis Tool Company, Waynesboro, Pa. Filed May 3, 1962, Ser. No. 192,205 13 Claims. (Cl. 51-105) This invention relates to work rests for grinding machines, particularly work rests which are operated at one pressure for one portion of a grinding operation and at another pres-sure for another portion of the grinding operation.

The amount of force required to support a workpiece at different points in a grinding operation varies in accordance with the requirements of the particular type of work being ground. It is the purpose of this invention to provide means for exerting different forces on the work by the work rest at selected points in the progress of a grinding operation. The work rest pressure on a workpiece may vary and the points on the grinding cycle at which the pressure changes, may vary in accordance with requirements of a particular workpiece.

In the past, this has been accomplished by successively connecting pressure lines to a work rest, each line being connected through a different relief valve. Another device consisted of a pivotally mounted work rest assembly which was held against the work by operating pistons, with a low pressure on the piston for a preliminary grinding operation and a high pressure for the finish grinding operation.

This invention represents an improvement over the first type of multi-prcssure work rests in that each work rest shoe is advanced by means of a spring operated cam which, in turn, engages a reset piston, the different pressures being effected by subjecting the cam reset piston to different pressures opposing the spring which will determine the force exerted by the spring on the cam and thus the force exerted by the cam against the work rest shoe.

This invention represents'an improvement over the secand type of multi-pressure work rests in that the pressure is applied to the work rest shoe in a direct manner rather than through the pivoted bracket on which the work rest is mounted.

It is, therefore, an object of the present invention to provide a work rest operable to exert different forces on a workpiece.

Another object is to provide a work rest in which the actuating pressure is provided by resilient actuating means.

Another object is to provide a work rest in which the operation of the resilient means is controlled by fluid pressure.

Another object is to providea work rest in which the pressure exerted on a workpiece is changed by changing the hydraulic back pressure which controls the resilient actuating means.

FIG. 1 is a hydraulic and electric diagram.

FIG. 2 is an end elevation of a cam operated work rest.

In FIG. 2, frame is mounted on work carriage 11. The upper work engaging shoe in frame 10 is slidably mounted for horizontal movement. The lower work engaging shoe 16 is supported on arm 17 pivotal-1y supported on frame 10. Shoe 15 is mounted on plunger 18. Shoe 16 is actuated by plunger 19 through adjusting screw 20 in lu 21. Plungers 18 and 19 both have the same type of actuating mechanism. Therefore, only the actuating mechanism for plunger 18 will be described. In FIG. 1, where both actuating means are shown, the corresponding element of each plunger will be identified by the same reference numeral.

The actuating means for plunger 18 consists of housing having an opening 31 in which is slidably mounted a See cam 32. One end of cam 32 is in abutting relation with spring 33. The other end of cam 32 is in abutting relation through piston rod 34 of piston 35 in cylinder 36 which is a part of housing 30. The head end of cylinder 36 has an adjustable stop member 37 which determines the limited movement of piston 35 in one direction.

One end of plunger 18 extends through housing 30 to engage the inclined face of cam 32. Plunger 18 is held against cam 32 by spring 22 which also retract-s plunger 18 when cam 32 is reset. This rest is similar to that disclosed in US. Patent 3,118,258, granted January 21, 1964. The means for advancing and retracting grinding wheel 40 consists of a feed screw 41 having a piston 42 at one end slidably mounted in cylinder 43. Feed screw 41 is connected through a gear 44, shaft 45, gear 46, and worm 47 on shaft 48 which is rotatable by means of hand wheel 49. Gear 50 on shaft 48 engages a rack or screw 51 which is movable axially by means of piston 52 in cylinder 53. The wheel support represented by portion 55 may be advanced and retracted with feed screw 41, or relative to said feed screw 41 by rotation of shaft 45.

Operation The feed movement is started by closing infeed limit switch 3L3 by means of a suitable operating lever. Closing limit switch 3LS completes a circuit to energize relay 5CR.

Relay contact 5CR2 completes a circuit to energize infeed valve solenoid 2. Relay contact SCRl is a holding contact to maintain the circuit through limit switch contact 6LS2 to relay SCR after limit switch 3LS has been released.

Energizing valve solenoid 2 shifts feed pilot valve to the right, directing fluid under pressure to the right hand end of feed reversing valve 61. Valve 61 shifts to the left to direct fluid under pressure to the head end of rapid feed cylinder 43. Piston 42 and cylinder 43 advance wheel support 55 and grinding wheel 40 into operative relation with workpiece W. When piston 42 reaches the end of its stroke, exhaust pressure in the rod end of cylinder 43 drops and valve VP is shifted to change the fluid connection to round out valve 75 and the head end of feed cylinder 53 from exhaust to pressure to shift piston 52 and screw 51 to the left. The movement of screw 51 in engagement with gear 50 rotates shaft 48 to move wheel support 55 relative to feed screw 41 for a grinding feed. During this portion of the feed movement, hand wheel 49 rotates with shaft 48.

At a predetermined point in the grinding operation, cam on hand wheel 49 actuates limit switch 718 which completes a circuit from normally closed relay contact 6CR1 to energize timer clutch relay TR. Relay contact TRl completes a circuit to energize relay 7CR. Relay contact TR2 completes a circuit to hold relay TR. After a predetermined interval, normally closed relay contact TR3 times open and opens the circuit through normally closed relay contact 8CR1, to deenergize relay 26CR.

Relay contact 7 0R! completes a circuit to energize round-out valve solenoid 3 and shifts round out valve .to the right, cutting off the supply of fluid under pressure to the head end of cylinder 53, stopping the advance of wheel support 55 and grinding wheel 40, for a sparkout period.

Deenergizing relay 260R opens the circuit through relay contact 26CR2 to deenergize work rest reset valve solenoid 14.

Selector valve returns to central position, blocking the flow of fiuid through valve 80 to cylinder 36, leaving as the only source of fluid under pressure for operating the work rest, the permanent low pressure supply from the pump through restrictions 81 and 82. This fluid is under a pressure which exerts an lesser force on piston 35 and one end of cam 32 than that exerted in the opposite direction on the other end of cam 32. by spring 33. Cam 32 is thus allowed to advance at a slower rate and to ad- Vance plunger 18 to engage workpiece W under a suitable pressure for the remainder of the grinding operation. The movement of piston 35 and cam 32 is limited by stop member 37 which is adjusted to step piston 35 with cam 32 in a position in which it has advanced plunger 18 and 'shoe 16 to a position corresponding to the finished size of workpiece W.

The feeding movement of piston 52 and associated parts continues until cam 71 on hand wheel 49 actuates feed com letion limit switch 6LS, closing limit switch contact oLSl and completing a circuit to energize relay ZICR. 'Relay contact 27CR1 completes a circuit through normal- 'ly closed relay contact ZGCRl to energize relay SCR. Normally closed relay contact 8CR1 opens in the circuit to relay 2 6CR which was previously opened when relay contactTR3 timed open.

Closing relay contact 8C'R2 completes a circuit to energize work rest valvesolenoid t, shifting said valve to the right and connecting cylinder :36 with exhaust so that the 'full pressure of spring 3-3 is applied .to make sure that piston '35 is firmly engaged with stop member 37 and that plunger 18 and shoe 15 are in their maximum advanced .position.

As indicated previously, the above description applies equally to shoe 16, arm 17 and plunger 19.

Whenlimit switch contact 6LS1- is closed, limit switch contact 6LS2 opens to deenergize relay 50R. Relay contact 'SOR'Z opens to deenergize infeed valve solenoid 2.

lInfeed valve 60 is shifted to the left, directing iluid under pressure to the left end of feed reversing valve 61, shifting said valve to the right and directing fluid under pressure to the rod end of cylinders 43 and 53 to reset pistons 42 and 52 respectively and wheel support 55.

The resetting movement of piston 52 reverses hand wheel 49 and releases limit switch 6L3, opening limit switch contact-6LS1 and closing limit switch contact 61582. Opening limit switch contact 6LS1 deenergizes relay 270R, opening relay contact 27CR1 and deenergizing relay SCR.

Normally closed relay contact SC'RI completes a shcuit from normally closed timer relay contact 3 to energize relay 26'C'R. Relay contact 26CR2 closes to energize work rest valve solenoid 1-4, shifting valve 80 to the left and connecting the feed end of cylinder 36 with full pump pressure. Piston '35 moves to reset cam 32 against spring 31, releasing plunger 18 which is retracted along with shoe 15 by means of spring 2 2.

Retracting wheel support 55 closes limit switch 2L3 to complete a circuit to energize relay GCR. Normally closed relay contact scar opens a circuit through holding contact TRZ to deenerg-ize timer clutch rel-ay TR and reset the timer. Timer relay contact TRl opens to deenergize relay 7 R. Relay contact 7CR1 opens to deenergize valve solenoid 3, resetting valve 75 to the left. Normally closed relay contact TR3 closes to complete a circuit through normally closed relay contact 8CR1 to energize relay 266R. 'Relay contact 260112 closes to energize work rest valve solenoid 14 which shifts valve 80 to the left'and directs full pressure to the head end of work rest cylinder 36 to reset plunger 18 and shoe 15.

I claim:

1. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, and a fluid pressure actuated piston in abutting relation with the other end of said cam' 2. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding rrteans for advancing said grinding wheel toward a workpiece for agrinding operation, a work rest for supporting a Work piece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end or said cam, and means to apply a low back pressure to said piston during part of a grinding operation and to apply a high back pressure: on said piston during another part of the grinding operation.

3. In a grinding machine, grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a wo kpiece for 3 grinding operation, a work rest for supporting a work: piece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting fold tion with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pres= sure actuated piston in abutting relation with the other end of said cam, a valve operable in different ositions to apply different pressures on said piston, and control means responsive to said feeding means to actuate said valve at predetermined points in the advance of said grinding wheel during a grinding operation.

4. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, and means to apply an adjustable back pressure to said piston so that said cam exerts a low pressure on said shoe during part of the grinding operation and a high pressure on said shoe during another part of the grinding operation.

5. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, means to apply an adjustable back pressure to said piston so that said cam exerts a low pressure on said shoe during part of the grinding operation and a high pressure on said shoe during another part of the grinding operation, and control means actuated by said feeding means to change from one pressure to another.

6. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, a valve operable in different posi-.

tions to apply'pressure on said piston less than said op.

posing spring pressure,'exhaust pressure L0 permit full spring pressure on said cam, and to apply pressure greater than said opposing spring pressure to reset said cam and releasing said shoe, and control means responsive to said feeding means to actuate said valve at predetermined points in the advance of said grinding wheel during a grinding'operation.

7. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, and means for supplying fluid under pressure to the end of said piston opposite said cam to reset said cam against said spring.

8. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a workpiece against said grinding wheel, a work rest shoe on said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, a supply of fluid under pressure, and a valve for controlling the pressure on one end of saidpiston to modify or overcome the elfect of said spring on said cam and said work rest shoe.

9. In a grinding machine, a grinding wheel support, a grinding wheel on said Wheel support, feeding means for advancing said grinding wheel toward a workpiece, a work rest for supporting a workpiece for a grinding operation comprising a base, a plunger slidably mounted in said base and having means thereon for engaging and supporting a workpiece, means for holding said plunger against said workpiece comprising a free cam slidably mounted for movement in a direction transversely of the direction of movement of said plunger and having an inclined surface in operative engagement with said plunger, a first resilient means for holding said plunger against said cam, a second resilient means in abutting relation with one end of said cam for moving said cam in a direction to advance said plunger against a workpiece, a piston in abutting relation with the other end of said cam, means for supplying fluid under pressure to one end of said piston, a valve for controlling the flow of fluid under pressure to said piston, said valve being connected to different pressures including exhaust and operable in one position for directing fluid under pressure greater than said second resilient means for resetting said piston and said cam and in another position to connect said piston with a pressure less than that exerted by said second resilient means, said valve being operable in another po i i n to connect said piston wi h exhaust so that said second resilient means acting through said cam applies its full power on said plunger,

10. In a grinding machine, a grinding wheel support, a gr nding whe l on. i w eel pport, eeding mean for a v n ing a gr n g W l owa d a workpi c a work rest for supporting a workpiece for a grinding op e tion cn n ng a ba e, a pl nger slidably mo te in said base and having means thereon for engaging n upp rting a w rkpi c mean fo h l ng id plunger against said workpiece comprising a free earn slidably mounted for movement in a, direction transversely of the direction of movement of said plunger and having an i cl ne s f c in p r t ve e gag me t with said plunger, a first resilient means for holding said plunger against said cam, a second resilient means in abutting relation with one end of said cam for moving said cam in a direction to advance said plunger against a workpiece, a piston in abutting relation with the other end of said cam, means for supplying fluid under pressure to one end of said piston, a valve for controlling the flow of fluid under pressure to said piston, said valve being connected to different pressures including exhaust and operable in one position for directing fluid under pressure greater than said second resilient means for resetting said piston and said cam, and in another position to connect said piston with a pressure less than that exerted by said second reslient means, said valve being operable in another position to connect said piston with exhaust so that said second resilient means acting through said cam applies its full power on said plunger, and control means operable by said feeding means for successively connecting said piston to said different pressures at predetermined points in the movement of said grinding wheel support.

11. In a grinding machine, a grinding wheel support, a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece, a work rest for supporting a workpiece for a grinding operation comprising a base, a plunger slidably mounted in said base and having means thereon for engaging and supporting a workpiece, means for maintaining a pressure of said plunger against said workpiece comprising a free cam slidably mounted for movement in a direction transversely of the direction of movement of said plunger and having an inclined surface in operative engagement with said plunger, a first resilient means for moving said cam in a direction to advance said plunger, a second resilient means for holding said plunger against said cam, a piston in the path of said cam, a supply of fluid under diiferent pressures, a valve for controlling the flow of fluid under pressure to one end of said piston, control means responsive to said feeding means to actuate said valve to one position for directing fluid under one pressure for retarding the movement of said piston and cam and thus exerting a relatively low pressure on said plunger, control means for positioning said valve in another direction to connect said piston with a lower pressure, thereby increasing the force exerted by said first mentioned resilient means on said plunger, and control means for positioning said valve in a third position for directing fluid under pressure against said piston greater than that exerted in the opposite direction by said first resilient means, to reset said cam against said first resilient means and to permit said second resilient means to retract said plunger.

12. A work rest for supporting a workpiece for a grinding operation comprising a base, a plunger slidably mounted in said base and having means thereon for engaging and supporting a workpiece, means for maintain ing unform pressure of said plunger against said workpiece comprising a free cam slidably mounted for movement in a direction transversely of the direction of movement of said plunger and having an inclined surface in operative engagement with said plunger, resilient means for moving said cam in a direction to advance said plunger, another resilient means for holding said plunger against said cam, a fluid pressure actuated piston in the path of said cam, and means for supplying fluid under P e e 0 the n of a d pi n oppo e aid. am to reset said cam against the first mentioned resilient means, I

1 n gr nding mach n a grinding wheel s pp r a grinding wheel on said wheel support, feeding means for advancing said grinding wheel toward a workpiece for a grinding operation, a work rest for supporting a work.- p e g in t sai grin ing wh el, a work rest shoe n said work rest for engaging and supporting a workpiece, a free cam engaging said work rest, a spring in abutting relation with one end of said cam for shifting said cam 7 and advancing said shoe against said workpiece, a fluid pressure actuated piston in abutting relation with the other end of said cam, a supply of fluid under diflerent pressures, 'a selector valve for controlling the flow of fluid under pressure, control means responsive to said see References Cited by the Examiner UNITED STATES PATENTS 1,961,091 5/1934 Smith -et a1. 2,419,170 4/1947 Silven 51--238.1 2,509,368 5/1950 Price. 2,567,620 9/1951 Silven 51238.1 2,744,366 5/1956 Arp 51238.1 2,799,977 7/1957 Jones et' a1. 2,927,408 3/1960 Cann. 3,118,258 1 1/1964 Price et a1.

LESTER MJSWINGLE, Primary Examiner. JOHN C.'CHRISTIE, Examiner. 

2. IN A GRINDING MACHINE, A GRINDING WHEEL SUPPORT, A GRINDING WHEEL ON SAID WHEEL SUPPORT, FEEDING MEANS FOR ADVANCING SAID GRINDING WHEEL TOWARD A WORKPIECE FOR A GRINDING OPERATION, A WORK REST FOR SUPPORTING A WORKPIECE AGAINST SAID GRINDING WHEEL, A WORK REST SHOE ON SAID WORK REST FOR ENGAGING AND SUPPORTING A WORKPIECE, A FREE CAM ENGAGING AND SUPPORTING A WORKPIECE, RELATION WITH ONE END OF SAID CAM FOR SHIFTING SAID CAM AND ADVANCING SAID SHOE AGAINST SAID WORKPIECE, A FLUID PRESSURE ACTUATED PISTON IN ABUTTING RELATION WITH THE OTHER END OF SAID CAM, AND MEANS TO APPLY A LOW BACK PRESSURE TO SAID PISTON DURING PART OF A GRINDING OPERATION AND TO APPLY A HIGH BACK PRESSURE ON SAID PISTON DURING ANOTHER PART OF THE GRINDING OPERATION. 